We're building a SaaS app. I'd like use another SaaS to handle the customer service parts of the app. Specifically, I'm looking for:
Single sign-on. When the customer signs into our app, they should be able to click a "Help" link and already be signed into the other service.
A good community. Users should be able to post questions and have other users answer them. Ideally, we'd have something Stack Overflow-like.
Documentation. I want a place to write a user guide. It needs to accessible only behind the sign in. It should be searchable.
Knowledge base. It would be nice to have a place to write how-to articles. Could just be part of the documentation system.